AI War:Cross Planet Attack

How Do I Prepare For Cross-Planet Attacks?

Q: I just got the message cross-planet attack in 15 minutes (180 or so ships). I don't recall this being covered in the tutorial. Is there any way to know where the attack will happen? How would one realistically prepare for it? Split my entire fleet between my planets?

A: Cross-planet attacks will occur periodically, and basically what that means is that a certain number of ships on the enemy planets will become "freed" and will go into attack mode instead of defending their current planet. Or, to put it another way, in the example above the Threat is about to go up by 180 in 15 minutes, and those 180 ships may attack anywhere at any time after that point (using the normal attack and retreat logic of the AI, which is the same sort of thing that happens if you kill a planet's command station without first killing all its ships).

In the example above, 180 ships is not really that dangerous, and just making sure that there are plenty of turrets and tractor beams on all the enemy-bordering wormholes will probably handle it. If the number was much larger (which happens as the AI Progress gets higher in the game), you could be looking at 1,000+ or even 2,000+ ships in a cross-planet attack, depending on your difficulty level and just how high the AI Progress has gotten. In those cases, splitting your fleet between the most important planets to defend, while also investing heavily in fortifying wormholes with tractor beams and turrets is a great idea.

Even the really huge cross-planet attacks are quite survivable because they often tend to be very diffuse, coming at you from every direction. So they generally don't pose much risk of just outright crushing your empire. However, they will find weaknesses and holes in your defenses, and slip in through all sorts of sides at once, which is a unique challenge that you don't face many other times during the game. And if they can't find many weak spots, and you fail to kill them all as they come in, they'll escape back out into the galaxy to try again, as with any attacking ships.

AI_War:Fleet_Command

How Do Cross-Planet Attacks Work?

Q: I just got the message cross-planet attack in 15 minutes (180 or so ships). I don't recall this being covered in the tutorial. Is there any way to know where the attack will happen? How would one realistically prepare for it? Split my entire fleet between my planets?

A: Cross-planet attacks will occasionally be launched by the AI -- usually not more frequently than every 45 minutes or so, and often only once every few hours. A cross planet attack simply consists of a certain number of ships (which you will be told, and generally ranges from several hundred to several thousand ships) all becoming "free" all at once.

On most of the AI planets, most of the time, the ships are in guard mode, or are moving between special forces guard posts. So most of the AI ships are not actively able to attack you, they will just defend when you attack them (the special forces of course sometimes will attack, but they are not very direct or frequent about it). When a cross-planet attack occurs, then X number of the guarding ships become free, which makes them contribute to the Threat counter immediately. They will then be coming to attack your planets at any time, from any direction -- you don't know which AI planets these would be coming from.

Some players have concerns about making high-level AI planets get lots of ships by being on alert, for fear of cross-planet attacks. While putting high-level AI planets on alert can be bad if you need to go through that planet or later want to capture it, there are no consequences relating to cross-planet attacks. The cross-planet attack is, rather, based on the tech level of the AI at the time the attack is declared. If the tech level of the two AIs differ, then you can't be certain which level the attack will be. For example, if the current tech level of the incoming enemy waves is II, then that is the tech level that the cross-planet ships will be.

AI_War:Fleet_Command

What Is The Underlying Calculation For Cross Planet Attack Size?

A: The general formula is thus:

    difficulty = DifficultyOfFirstAIPlayer
    numberOfShips = AIProgressionLevelEffective * difficulty * humanPlayerNumberMultiplier
    AIProgressionLevelEffective = AIProgressionLevelTotal - NegativeAIProgressionOffset
    if(AIProgressionLevelEffective < AIProgressionLevelFloor)
       AIProgressionLevelEffective = AIProgressionLevelFloor
    difficulty = AIDifficulty * 0.8
    humanPlayerNumberMultiplier = 1 + ( humanPlayerCount - 1 ) * 0.33

(that's psuedocode, of course, as you can tell by the order of lines, but it's easier to understand in this format)

So if you have:

    140 Total AIP
    40 Negative AIP
    (AIP floor is negligible in this case)
    7.0 difficulty
    2 human players

The formula gives =

    (140 - 40) * (7.0 * 0.Cool * (1 + (2 - 1) * 0.33)
    =
    100 * 5.6 * 1.33
    =
    744.8 (rounds down to 744)
    Or, with only 1 human player it's 560.

AI_War:Fleet_Command